many a ponds have been destroyed to 50 year rains. i highly recommend an emergency spillway. many ponds have small overflow areas, but also a biiigggg emergency spillway. i designed mine to have a biiiggg emergency spill way, with it also being the overflow (seeded with grass of course to prevent erosion). one key thing i did that i've seen some other ponds not doing...i directed the spill way drainage AWAY from the back slope of the dam. i've seen a few ponds that the over flow water erodes behind the dam and later on whamo...it cuts the corner of the dam out. easy dozer solution. mark